2 Cold Radiators - Hot Water System

Ron Schroeder

is there another screw slot inside that cap if there is try turning ig a couple of revolutions and turn power back on and see what happens, I had some simalar pumps in some greenhouses and every year I had to rotate them to get them to go.

Barry

2 Cold Radiators - Hot Water System

I recently purchased a rental home next door to my house. Now that heating season is here the boiler was fired up only to find the 2 radiators in the main floor bedrooms do not heat up at all. I had the boiler cleaned/serviced last month. It is a hot water system with a boiler that is about 15 years old. I already bled all the radiators in the house. The return pipes for those radiators get hot, I checked them from the basement. What should I look for when trying to determine the cause? Can I check the valves without draining the system and taking the valves off? Thanks!

Steamhead (in transit)

Measure the EDR

and tell us what circulator is on the system. Also if it's a converted gravity system. Maybe the circulator is too big, and the water is flowing thru those rads so fast it doesn't drop off any heat.

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Mike T., Swampeast MO

Are you certain that the hand valves on the radiators are fully open? Most turn counter-clockwise to open. There should be an arrow on the handle--even if not stated, turn the direction of the arrow to open.

If you can't turn the valve with moderate pressure try turning the opposite direction as the valve may already be open. If frozen, spray around the stem with WD-40 or similar. Wait a while and try turning. Repeat a few times if necessary. If you still can't get the valve to turn you'll need to disassemble and clean/replace the valve--draining the system is REQUIRED. Common hand valves don't give an indication of "open" or "closed" other than turning the valve--again counter-clockwise is almost always "open".

The branch pipes in the basement can feel rather hot via conduction from the mains. Feel the pipe right before the hand valve and also right after it leaves from the other connection. If both are cold, then there is no flow.

If you've turned the valve to the "open" position and there's still no heat, it's possible that the valve mechanism is broken--really no way to verify other than disassembly--again you MUST drain the system to disassemble.

Draining, filling and air purging a hot water system can vary from simple to an absolute PITA. If you're unfamiliar with such systems, I'd highly recommend you call in a pro familiar with hot water systems, not only for proper filling but for a good review of the system. As long as you don't ask too many questions they shouldn't have any problem showing you how to properly drain & fill your system as well as pointing out basic things to watch.

Barry

Thanks for the great advice, I am going to check things out again tonight. I am not sure the size of the circulator, although they do not warm up even the slightest so I am thinking it must be the valves. Is there a chance the pipes are blocked? Or is that unlikely?

Mike T., Swampeast MO

Very unlikely that the pipes are clogged. Only times I've seen severely corroded pipes in a hot water system is when galvanized pipe/fittings were used (instead of black iron/steel) during a modification or if there is a significant leak requiring lots of makeup water.

Hand valves frozen shut, circulator defective/improperly sized and inappropriate piping modifications are the most common causes.

Barry

I checked last night and now I think it is the circulator. When I put my hand on the pump I don't feel any vibration at all. I recently had it serviced so I would have thought they checked the pump. It is a Grundfos pump and it has a white switch which can be set to 2 or 3 ticks. What does this switch do? I will likely just call and have the pump replaced by a professional. Thanks for everyone's advice, I was ready to replace both radiator valves this weekend, did not even think about the pump. Thanks

Brad White_126

Grundfos

as with most wet rotor circulators, can be very quiet (one may have to burn their ear to hear them )

The switch you describe is the speed selector switch. Try turning it with a screwdriver and see if it clicks on. Is the circulator warm at least?

The fact that the switch is white indicates it is an older model. I have some and they still run fine but like any piece of equipment they do stop running eventually.

Try the switch and see what happens.

Barry

I put my hand on it and it never got warm, even after about 20 minutes. I did try the white switch and nothing happened. There is also a screw on the front face, what is that for? How difficult is it to switch the pump out?

Barry

Photo of circulator

I took the cap off the front of the circulator and turned the thermostat up. I did not see anything moving inside the circulator and my circuit tester tells me there is power going to the circulator. Seems like I could just order another pump and switch it out???

Brad White_118

Yes

I would switch it out. Was the bleeder screw always loose? It is weeping in the close-up. Maybe it heard your plans?

rob brown

pump

your on the right track, but tell me, did you check for power at the pump, or the relay? you might have a bad connection in the junction box of the pump. once you verify power, try using a flat screwdriver to turn the pump shaft under that plug. i had a customer whose pump would lock up every summer from non-use. gave it a spin and it ran fine all winter. this went on for at least 5 years. (cust. would not hear of replacing pump -"it's not even 10 years old!") good luck. rob

Barry

Thanks for all the advice. There does not seem to be a screw under the cover but I was able to spin the little metal piece in there with a pliers. It spun very easily, but am going to try again with a screwdriver, maybe I was spinning the wrong part. I did check the electrical and there is juice in both the relay and at the pump when the thermostat is on. I guess that does not mean there is not a bad connection somewhere in the pump. I found a new pump for $85 and am going to swap it out this weekend. How difficult will the swap be? Seems like it would be easy....

Steve L.

I have had many jobs with simular problems. The most commor cause is related to the radiator valves. Some hot water radiator valves have a tab on the handle the stops the stem at full open and full closed. (this type of valve is a quarter turn style). What often happens is that the tap on the handle gets bent over time. So what happens is that fully open and fully closed are no longer lined up correctly. Sometimes the tab has brokern clean off. In this case the handle of the valve will spin infiniatly.
If you have this problem you can turn up the thermostat for that zone of heat.
Then once you are certain that the boiler is up to temp and hot water is circulating, slowly turn the handle of the radiator valve. Be sure to alow time after each adjustment to see if the water is flowing.

Hope this makes sense.

Steve L.

Brad White_9

Easy

Just isolate and drain the piping immediately upstream and downstream of the circulator. (Sometimes easier said than done. The value of good quality isolation flanges will become apparent!)

Don't forget to disconnect the power! You are working near a nice ground (the piping). If you are not careful you will have two things in common with Arthur Fiedler:
1) You will be remembered as a great conductor and 2) you will also be dead.

The new circulators usually come with flat O-Ring gaskets which fit into the grooves in the circulator flange casting. Neat. I always keep a few spares kicking around. You may or may not have bolts (bolt kits follow the flanges, not the circulator) so if you have to replace them, get those. Cheap and beats having to run out at a critical time.

The whole job should take 15-20 minutes plus drain and fill time and allowing for some prying and hanger release to get some spring room to get the old circulator out and the new one in.

Steve L.

It would seem to me that if all but two radiators are heating it would not be due to a faulty circulator. (unless system doesn't have flow valves I guess).

Barry

Success!!

Thanks for everyone's advice. I put in a new grundfos circulator this weekend and everything works perfectly now. Both radiators that were cold previously are now getting hot. Thanks agian!

Brad White_9

Great, Barry

Glad to hear it, the feedback is appreciated. That must feel good, really good!